Summer's on its way, when the better weather and all that sport on the telly inspires us to get out there and get active - but all too often it can end in tears.

Nearly a quarter of UK adults will take up an activity after watching a major sporting event, such as Wimbledon, Euro 2008, or the Olympics, according to research for Crampex, the muscle cramp treatment.

While an online survey last year revealed that around 50 per cent of British holidaymakers took part in a spontaneous, dangerous activities like kite surfing or bungee jumping while abroad.

But sudden exercise - especially after an inactive winter - can result in injuries that derail an attempt to gain seasonal fitness and ruin summer fun.

"People coming in with a host of leisure-related injuries and saying 'I haven't done any sport or exercise for ages...' is incredibly common in the summer months," says personal trainer Kristoph Thompson.

"Trainers and physios call it 'summeritis' where people go crazy when they see a bit of sunshine, completely disregard or are ignorant of their fitness level, and throw themselves into sudden activity."

Injuries range from minor strains and sprains to torn tendons or ligament damage which can take months to heal, and at worst leave a permanent weakness.

Alan Watson is a chartered physiotherapist with the BiMal medical clinic at the Hogarth Health Club in London (www.thehogarth.co.uk). He says: "Many people assume that the fitness level they enjoyed last summer will miraculously have remained the same."

Sports enthusiasts aren't the only ones at risk from seasonal injuries - with keen gardeners and DIYers among those who can pay the price for over-enthusiastic activity.

Am I at risk?

If any of the following apply to you, follow the guide below before rushing out to exercise.

I've been a 'couch potato' all winter/find the gym boring and rarely go/only like exercising outdoors in good weather.

I've put on weight and think taking up sport again will be a good way to lose it.

I warm up by doing a bit of stretching for about a minute and test to see I'm ready by bending down to touch my toes.

I played lots of sport at school, and just rely on my good techniques and skill to help me stay free of injury when I occasionally play in the summer.

What can I do to avoid injury?

Get smart and prepare

See your GP if you are starting a new fitness plan and have not recently exercised.

Kristoph Thompson, sport spokesman for Crampex, adds: "If you think you're likely to get swept up in sporting enthusiasm in the months to come, try to do a small amount of preparation ahead of time.

"Even some low-impact exercise like swimming or cycling will help to get your body moving and enable those muscles to stretch and loosen."

Warm up and cool down

Alan Watson says: "It's quite common to be told, especially by men, that they feel embarrassed to stretch or warm up before taking part in sport or doing an activity. They worry that it looks as though they're taking themselves too seriously, and they feel inhibited by that."

He advises warming up for at least 10 minutes by exercising muscles for a few minutes at a steady pace, before gradually increasing to a brisk pace. This will increase the blood flow to your muscles, making them more flexible, and reducing the risk of muscle strains.

Don't over-do it

Kristoph Thompson says: "If you're taking part in sport after a long break or trying out a new activity do limit yourself to ashort session.

"Be realistic and honest with yourself about what you can achieve, you can increase your activity as you become fitter.

But start slowly and don't attempt to match the pace of experienced players."

Watch the weight

Watson says: "Few people recognise that weight gain will affect the performance of muscles. If someone has put weight on the stomach it limits the function of the abdominal muscles and in turn strains the back."

He advises ditching the outdated test for fitness - bending over to touch the toes. "Instead, doing a brisk walk or short run and checking how you feel is a much better guide."